The other day I chatted with a pregnant gal at the hair salon. She was about 20, sweet, pretty, and demure. Because I am always doing sociological fieldwork, I asked my hairdresser if she was married. No. But she has a fiance. As always in these situations, you just want to grab these young people by the lapels and say "Get to the altar! It's critical for your child." I didn't, of course -- because while I am a zealot for marriage, I'm not yet prepared to become a public nuisance.

I thought of that young lady again this morning when I read of the latest report from the National Center for Health Statistics. It seems that the rate at which unmarried women are having babies in America jumped dramatically in the past seven years. "In 2007, there were 1,714,643 babies born to unmarried women, an increase of 4 percent from 2006, and 26 percent higher than the number in 2002 (1,365,966)," the NCHS reports. Forty percent of births in America are now to unwed mothers. Rates are highest among Hispanic women (like the one at the salon).

Though we had a vigorous national discussion about unwed childbearing back in the 1990s -- "Murphy Brown" followed by "Dan Quayle Was Right" by Barbara Dafoe Whitehead in the Atlantic magazine a few years later -- our current preoccupation with gay marriage has distracted us. The issue of greater importance is the degree to which heterosexual men and women are choosing to become parents while unmarried. "If you see 10 babies in the room," Stephanie Ventura of the NCHS told the Washington Post, "four of them were born to women who are not married."

And while popular culture and supermarket checkout mags might give you the impression that wealthy, successful women are leading the way on single parenting, celebrities actually obscure the reality. Movie stars and pop singers do often abjure marriage, but most successful women do not. In fact, as Kay Hymowitz limned in her 2006 book, "Marriage and Caste in America," what we really have in this country is a caste system. At the top are the college graduates who nearly always get married before becoming pregnant. At the bottom are poor women of all races and backgrounds who routinely have babies before they marry (if they ever marry). "As of 2000," Hymowitz wrote, "only about 10 percent of mothers with 16 or more years of education -- that is, with a college degree or higher -- were living without husbands. Compare that with 36 percent of mothers who have between 9 and 14 years of education." And the new NCHS data suggest that the numbers have only gotten worse since 2000. The life prospects for children born into intact families are so dramatically different from those born into single-parent homes that it would seem a gross injustice if it resulted from anything other than the free choice of parents. Actually, it is a gross injustice to the children -- even if it is perpetrated by their parents.

By the age of 12, 78 percent of children living in non-married households have experienced one or more years of poverty. For children in intact families, the figure is 18 percent. Babies born to unwed moms are more likely to be premature, to face low birth weight, and to suffer other pathologies. Children who are raised in non-marital households have poorer school performance, more trouble with the law, more mental and emotional disturbances, more poverty, suffer more physical and sexual abuse, and are more likely to become unwed parents themselves. Here's Hymowitz again: "Children of single mothers have lower grades and educational attainment than kids who grow up with married parents, even after controlling for race, family background, and IQ."

Princeton sociologist Sara McLanahan, among others, has speculated about why less-educated young women do not wait for marriage. Perhaps they invest marriage with excessively lofty expectations for complete personal happiness and fulfillment? One of the unwed moms interviewed by the Post explained her decision not to marry the father of her 3-year-old this way: "He's a good dad and a good person, but he's just not right for me." Another offered that "I didn't want to pick the wrong person just to have a kid, so I just decided to go ahead and do it and work on the relationship later."

Young women, especially poorly educated ones, have gotten the idea that marriage is all about them -- about their romantic hopes. In fact, while marriage often does deliver on the promise of happiness for adults, it is only secondarily about adult happiness. It is primarily about safety and security for children. The old stigma against illegitimacy was harsh and led to its own kind of suffering. But it prevented narcissistic young people from impairing the lives of their children on a grand scale.